In general, the vinegared rice is produced by spreading cooked rice in a container such as a sushi-rice tub, by mixing by means of a rice paddle the cooked rice with sushi dressing in which vinegar, sugar, and the like are blended in a predetermined ratio that depends on the measure of the cooked rice, the sushi dressing being sprinkled on the cooked rice, and by cooling the cooked rice to human-body temperature using a paper fan or the like.
In this situation, it is said to be preferable to mix the cooked rice with the sushi dressing as if the cooked rice were sliced by the rice paddle. This is to apply as less load as possible to the cooked rice; mashing the surfaces of the cooked rice through friction caused by the rice paddle makes the rice sticky, thereby degrading the taste and texture thereof.
Meanwhile, at places, such as restaurants, hotels, and cooked-rice processing plants, where a great deal of cooked rice is consumed, because it is necessary to prearrange a great deal of vinegared rice at one time, the vinegared rice is produced by automatically mixing the cooked rice with sushi dressing by means of dedicated food processors.
For example, a food processor disclosed in Patent Literature 1 (Japanese Utility Model Application Publication No. H5-39433) is structured in such a way that a horizontal rotating-axle rotatably supports a sphere-shaped container on the main body of the processor and the container is rotated by means of predetermined mixing means. The processor is designed in such a manner that a supplying opening for a blower as cooling means is formed at the one end of the horizontal rotating-axle; at the other end of the horizontal rotating-axle, an air-discharging outlet for the container is formed; and air sent from the blower cools cooked rice in the container.
According to Patent Literature 1, by sending air into the container and rotating the container on the horizontal rotating-axle, the cooked rice and sushi dressing that have been put into the container are cooled and appropriately mixed with each other, whereupon a great deal of vinegared rice can be produced.
In such a food processor as described above, the operation of the mixing means and the cooling means are controlled by unillustrated controlling means. In other words, as represented in FIG. 8, the controlling means includes a mixing process in which, once cooked rice and sushi dressing are put into the container, the cooked rice and the sushi dressing are mixed by merely rotating the container over a certain-period of time, and a cooling process in which the cooked rice is cooled by repeating at a certain interval of time rotating and stopping of the container, sending air into the container; whereby vinegared rice can efficiently be produced within a period of time that is set. In addition, the setting of conditions for each process is implemented by an operator, an operational panel being operated by him or her, before the operation of the processor is initiated.
However, conventional food processors had a problem described below. That is to say, in a conventional food processor, standstill duration (t1) and rotating duration (t2) are set for the container in the cooling process; the standstill and the rotation of the container is considered as one cycle based on the set duration; and the cycle is repeated within duration that is set.
Moreover, as set forth above, the lower the temperature is, the lower the fluidity of cooked rice is, thereby creating difficulty in mixing the cooked rice. When the cooked rice in its low temperature is mixed, the surfaces of the cooked rice grains are mashed through contact between the surfaces of the cooked rice grains and the inner wall of the container or a mixing rod.
Therefore, in the case of operation, as represented in FIG. 8, that simply repeats the rotation and the standstill, the number of the rotation becomes unnecessarily large, thereby inducing the stickiness of the cooked rice. The stickiness caused in cooked rice degrades the taste and the texture of vinegared rice.